[PATCH] icount: get rid of static variable

[PATCH] icount: get rid of static variable

[Pavel Dovgalyuk]

This patch moves static last_delta variable into timers_state
structure to allow correct vmstate operations with icount shift=auto enabled.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
---
 softmmu/cpu-timers.c   |    5 +++--
 softmmu/icount.c       |    9 +++------
 softmmu/timers-state.h |    2 ++
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/softmmu/cpu-timers.c b/softmmu/cpu-timers.c
index cd38595245..34ddfa02f1 100644
--- a/softmmu/cpu-timers.c
+++ b/softmmu/cpu-timers.c
@@ -188,11 +188,12 @@ static const VMStateDescription icount_vmstate_adjust_timers = {
 
 static const VMStateDescription icount_vmstate_shift = {
     .name = "timer/icount/shift",
-    .version_id = 1,
-    .minimum_version_id = 1,
+    .version_id = 2,
+    .minimum_version_id = 2,
     .needed = icount_shift_state_needed,
     .fields = (VMStateField[]) {
         VMSTATE_INT16(icount_time_shift, TimersState),
+        VMSTATE_INT64(last_delta, TimersState),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/softmmu/icount.c b/softmmu/icount.c
index dbcd8c3594..21341a4ce4 100644
--- a/softmmu/icount.c
+++ b/softmmu/icount.c
@@ -176,9 +176,6 @@ static void icount_adjust(void)
     int64_t cur_icount;
     int64_t delta;
 
-    /* Protected by TimersState mutex.  */
-    static int64_t last_delta;
-
     /* If the VM is not running, then do nothing.  */
     if (!runstate_is_running()) {
         return;
@@ -193,20 +190,20 @@ static void icount_adjust(void)
     delta = cur_icount - cur_time;
     /* FIXME: This is a very crude algorithm, somewhat prone to oscillation.  */
     if (delta > 0
-        && last_delta + ICOUNT_WOBBLE < delta * 2
+        && timers_state.last_delta + ICOUNT_WOBBLE < delta * 2
         && timers_state.icount_time_shift > 0) {
         /* The guest is getting too far ahead.  Slow time down.  */
         qatomic_set(&timers_state.icount_time_shift,
                     timers_state.icount_time_shift - 1);
     }
     if (delta < 0
-        && last_delta - ICOUNT_WOBBLE > delta * 2
+        && timers_state.last_delta - ICOUNT_WOBBLE > delta * 2
         && timers_state.icount_time_shift < MAX_ICOUNT_SHIFT) {
         /* The guest is getting too far behind.  Speed time up.  */
         qatomic_set(&timers_state.icount_time_shift,
                     timers_state.icount_time_shift + 1);
     }
-    last_delta = delta;
+    timers_state.last_delta = delta;
     qatomic_set_i64(&timers_state.qemu_icount_bias,
                     cur_icount - (timers_state.qemu_icount
                                   << timers_state.icount_time_shift));
diff --git a/softmmu/timers-state.h b/softmmu/timers-state.h
index db4e60f18f..8c262ce139 100644
--- a/softmmu/timers-state.h
+++ b/softmmu/timers-state.h
@@ -43,6 +43,8 @@ typedef struct TimersState {
 
     /* Conversion factor from emulated instructions to virtual clock ticks.  */
     int16_t icount_time_shift;
+    /* Icount delta used for shift auto adjust. */
+    int64_t last_delta;
 
     /* Compensate for varying guest execution speed.  */
     int64_t qemu_icount_bias;

Re: [PATCH] icount: get rid of static variable

[Paolo Bonzini]

On 29/03/21 12:22, Pavel Dovgalyuk wrote:
> This patch moves static last_delta variable into timers_state
> structure to allow correct vmstate operations with icount shift=auto enabled.
> 
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> ---
>   softmmu/cpu-timers.c   |    5 +++--
>   softmmu/icount.c       |    9 +++------
>   softmmu/timers-state.h |    2 ++
>   3 files changed, 8 insertions(+), 8 deletions(-)

Queued, thanks.

Paolo